1. Field of the Invention
The present invention relates to fastening systems and feed apparatus therefor and, more particularly, to a continuous staple feed system for a staple gun fastener.
2. History of the Prior Art
For many years, fastening tools have been used for rapidly fastening together structural members such as wooden studs, wooden sheets, and the like. These fastening tools have found widespread popularity in the building and manufacturing industries because they provide an economical means for assembling a wide variety of articles. Two of the most common forms of fastening tools are nail guns and staple guns that utilize "racks" of fastening elements such as nails or staples. The racks are fed into the gun and aligned beneath an actuation hammer for discharge of individual elements therefrom. In many manufacturing set-ups, it is preferable that the gun be disposed in a horizontal orientation, parallel to the surfaces of structural members to be fastened. Structural members may move beneath the gun on a conveyor belt, so that as nails or staples are discharged vertically from the gun, they penetrate the structural members perpendicular to their surfaces.
Generally, the type of construction and the size of members to be fastened are the determining factors as to which type of automatic fastener system is utilized. In residential construction, for example, the most common type of fastener is the nail which is often discharged from a pneumatic gun which drives the nail through wooden studs and/or sheets of wood, gypsum, or the like to effect an assembly for structural and functional use. When less structural support is needed, or when the assembled sheets are thinner in size, U-shaped staples are often utilized. Staple guns provide the same efficient operation as nail guns by discharging individual staples from multiple staple racks that are fed into the staple gun.
Existing automatic fastener guns have serious problems with their systems for feeding fastener elements into the guns. During high speed operation of such fastener guns, it is of critical importance that there be an uninterrupted supply of fastener elements. During the feeding process, the nail or staple must be positioned with precision beneath the actuation head of the fastening gun. Only when properly positioned will the fastening member be discharged from the gun in the proper orientation and with sufficient force to drive it through the members to be fastened.
When the fastening element is not properly aligned beneath the actuation head, problems such as jamming occur. A jammed gun can cause undue delay in operation, lost efficiency, wasted manhours, and often results in damage to the fastening gun with its attendant cost of repair. Jamming often occurs because of improper feeding of the fastening elements to the gun itself. Because the fastening elements are generally provided in racks which maintain the alignment of the individual elements within each rack, such jamming problems rarely occur in midrack. If a constant feed force is maintained on the rear of the rack, the rack smoothly advances, and individual fasteners are properly discharged from the gun.
When additional racks of fastening elements must be added, however, it is generally necessary to remove the feed force upon loaded racks to allow additional racks of fastening elements to be loaded. Once the racks are loaded, the feed forces, usually generated by a spring, are then restored. In addition to causing a delay in the operation of the gun, this "intermittent" feed force operation causes numerous other problems, especially at the transition points between racks. First, there can be inconsistencies in the movement of the fastening elements within the gun, causing a fore-and-aft misalignment under the actuation head. Second, the racks of fastening members can become skewed when the feed force is reapplied, causing additional misalignment problems. These are but a few of the problems that have plagued the automatic fastener industry.
For these and other reasons, a variety of improvements have been set forth, which generally address methods of providing a continuous feed of fastening members to the gun. Some of these approaches are set forth and shown in various U.S. patents. For example, U.S. Pat. No. 3,189,220 to Mullaney teaches a staple feed system that is transverse to the movement of the staples through the gun. Similar systems are seen in nail gun feed systems.
U.S. Pat. No. 4,326,661 to Maurer et al teaches a nail gun having a standard nail gun feed, the nails being angulated relative to the feed track. The use of angulated nails is clearly accepted in the industry, but it has not to date been deemed acceptable for staples.
U.S. Pat. No. 4,746,046 to Frye teaches a motor-driven feed for staples supplied in racks. Although the feed applies constant pressure, it requires a separate, external feed system and power source.
U.S. Pat. No. 5,065,930 to Kennedy teaches an external, pneumatically operated spiral feeding system. The spiral feeding system shown in Kennedy is particularly adapted for stapling lattices, pallets, fence panels and the like which move on a conveyor belt past a permanently mounted, stationary fastener gun.
As seen by the existing systems discussed above, automatic feeding of both staples and nails has received wide-spread attention. To date, all such systems utilize motorized feeds with their attendant reliability problems, expenses, and complications. It would be advantageous, therefore, to have a single, reliable automatic feeding system for such fastening elements that provides a gravitational feeding system which utilizes gravitational forces to feed the fastening members to a staple gun that may be disposed in a horizontal relationship relative to the members to be fastened. The present invention provides such a system by providing an in-line, arcuate feed track aligned to present fastening members in a horizontal position beneath the actuation head of a fastener gun, in a reliable and effective manner using only the force of gravity.